Adaptive convolution method in long term evolution networks

ABSTRACT

A method, system, and medium are provided for dynamically enabling and disabling cyclic prefix within a long-term evolution (LTE) channel. A base station receives channel quality indication (CQI) reports indicating levels of ISI within the LTE channel. The base station determines whether the levels of ISI within the LTE channel are greater than, equal to, or less than a predetermined threshold level of ISI for the LTE channel. Based on the determination, the base station either enables or disables cyclic prefix within the LTE channel. In addition to levels of ISI, numbers of roaming users or cell edge users utilizing the LTE channel may affect whether cyclic prefix is enabled or disabled within the LTE channel.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application, entitled “Adaptive Convolution Methods in Long TermEvolution Networks,” is a continuation application of pending U.S.application Ser. No. 13/796,919, filed Mar. 12, 2013 and entitled also“Adaptive Convolution Methods in Long Term Evolution Networks.” Theentirety of the afore-mentioned application is incorporated by referenceherein.

SUMMARY

This Summary is provided to introduce a selection of concepts in asimplified form that are further described below in the DetailedDescription. Embodiments of the present invention are defined by theclaims below. This Summary is not intended to identify key features oressential features of the claimed subject matter, nor is it intended tobe used as an aid in isolation to determine the scope of the claimedsubject matter.

In brief and at a high level, this disclosure describes, among otherthings, the dynamic enablement and disablement of cyclic prefix in along-term evolution (LTE) channel so as to eliminate intersymbolinterference (ISI) and distortion levels within the LTE channel. At abase station, an indication of levels of ISI within a channel isreceived, and the base station utilizes such information to determinewhether to dynamically enable or disable a downlink direction cyclicprefix within the channel.

When inputs are received indicating that ISI is above a predeterminedthreshold level, cyclic prefix is enabled. If the level of ISI is lessthan or decreases below the predetermined threshold level, however,cyclic prefix is dynamically disabled, resulting in more availablebandwidth for users. In embodiments, other conditions, such as, forexample, the number of cell edge or roaming users or the distortionlevels affecting groups of users, may influence the determination toturn on or off cyclic prefix.

BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS

Illustrative embodiments of the present invention are described indetail below with reference to the attached drawing figures, andwherein:

FIG. 1 depicts a block diagram of a mobile device in accordance with anembodiment of the present invention;

FIG. 2 depicts an illustrative networking environment suitable toimplement embodiments of the present invention;

FIG. 3 depicts a diagram of an exemplary cyclic prefix in accordancewith embodiments of the present invention;

FIG. 4 depicts a flow diagram illustrating a method for dynamicallyenabling cyclic prefix within a wireless channel based on levels of ISIwithin the wireless channel according to embodiments of the presentinvention; and

FIG. 5 depicts a flow diagram illustrating a method for dynamicallydisabling cyclic prefix within a wireless channel based on a number ofcell edge users communicating with a base station via the wirelesschannel according to embodiments of the present invention.

DETAILED DESCRIPTION

The subject matter of select embodiments of the present invention isdescribed with specificity herein to meet statutory requirements. Butthe description itself is not intended to define what we regard as ourinvention, which is what the claims do. The claimed subject matter mightbe embodied in other ways to include different steps or combinations ofsteps similar to the ones described in this document, in conjunctionwith other present or future technologies. Terms should not beinterpreted as implying any particular order among or between varioussteps herein disclosed unless and except when the order of individualsteps is explicitly described.

Throughout this disclosure, several acronyms and shorthand notations areused to aid the understanding of certain concepts pertaining to theassociated system and services. These acronyms and shorthand notationsare intended to help provide an easy methodology of communicating theideas expressed herein and are not meant to limit the scope of thepresent invention. The following is a list of these acronyms:

-   -   CDMA Code Division Multiple Access    -   CQI Channel Quality Indication    -   eNodeB Evolved NodeB    -   EvDO Enhanced Voice-Data Only    -   GPRS General Packet Radio Service    -   GSM Global System for Mobile Communications    -   HSDPA High-Speed Downlink Packet Access    -   ISI Intersymbol Interference    -   LTE Long Term Evolution    -   OFDM Orthogonal Frequency-Division Multiplexing    -   RF Radiofrequency    -   TDMA Time Division Multiple Access    -   UE User Equipment    -   UMTS Universal Mobile Telecommunications System    -   WCDMA Wideband Code Division Multiple Access

Further, various technical terms are used throughout this description.An illustrative resource that fleshes out various aspects of these termscan be found in Newton's Telecom Dictionary, 25th Edition (2009).

Embodiments of our technology may be embodied as, among other things, amethod, system, or set of instructions embodied on one or morecomputer-readable media. Computer-readable media include both volatileand nonvolatile media, removable and non-removable media, andcontemplate media readable by a database, a switch, and various othernetwork devices. Computer-readable media include media implemented inany way for storing information. Examples of stored information includecomputer-useable instructions, data structures, program modules, andother data representations. Media examples include RAM, ROM, EEPROM,flash memory or other memory technology, CD-ROM, digital versatile discs(DVD), holographic media or other optical disc storage, magneticcassettes, magnetic tape, magnetic disk storage, and other magneticstorage devices. These technologies can store data momentarily,temporarily, or permanently.

Examples of the present invention are directed toward methods, systemsand computer-readable storage media for use in dynamically turning on oroff cyclic prefix in a downlink LTE channel in order to eliminate orreduce ISI within the LTE channel. Initially, a threshold level of ISIfor the channel is predetermined by, for example, the network (i.e.,based on signal quality measurement reports) or a service provider. Thethreshold level indicates an amount of ISI above which cyclic prefixshould be turned on, and an amount of ISI below which cyclic prefixshould be turned off.

When inputs are received indicating that ISI is above a predeterminedthreshold level, cyclic prefix is enabled. If the level of ISI is lessthan or decreases below the predetermined threshold level, however,cyclic prefix is dynamically disabled, resulting in more availablebandwidth for users. In embodiments, other conditions, such as, forexample, the number of cell edge or roaming users or the distortionlevels affecting groups of users, may influence the determination toturn on or off cyclic prefix.

In one aspect, a base station receives input from mobile communicationdevices (i.e., signal quality measurement reports) indicating levels ofISI within a channel. Based on the input, the base station may determinethat the level of ISI within a channel is above a predeterminedthreshold level of ISI for the channel and dynamically enable cyclicprefix within the channel.

In a second aspect, the base station receives input from mobilecommunication devices indicating levels of ISI within a channel. Basedon the input, the base station may determine that the level of ISIwithin the channel is below a predetermined threshold level of ISI forthe channel and dynamically disable cyclic prefix within the channel.

In a third aspect, the base station receives input from mobilecommunication devices indicating a number of cell edge users or roamingusers utilizing a wireless channel. Based on the input, the base stationmay determine that the number of cell edge users or roaming usersutilizing the channel is above a threshold number. The threshold numbermay be predetermined by a service provider or the network, based on, forexample, a need to maintain minimally-acceptable data and voicetransmission speeds for such users. In particular, the threshold numbermay be a number at or above which a particular channel cannot support agiven user (e.g., roaming users). Upon making the determination, thebase station is configured to dynamically disable cyclic prefix withinthe channel. Disabling cyclic prefix should increase user throughputs byproviding increased bandwidth to cell edge and/or roaming users.

As way of background, cyclic prefix is a well-designed and simplifiedway to mitigate ISI among OFDM symbols and remove distortion in wirelesschannels. In particular, cyclic prefix refers to the prefixing of asymbol with a repetition at the end. When cyclic prefix is enabledwithin a channel, circular convolution is introduced. When cyclic prefixis disabled within a channel, linear convolution is introduced. Linearconvolution is inherently provided in LTE channels.

Turning to FIG. 3, an exemplary diagram of a cyclic prefix insertion isdepicted. As shown, the cyclic prefix includes the end of the symbol 320prefixed to the beginning of the symbol 320. The cyclic prefix acts as aguard interval 310, reducing the effect of the delay in the amount oftime it takes for a symbol to reach a receiver, the delay increasing asmultipath propagation increases. By increasing the time in which asymbol is allowed to reach a receiver (i.e., inserting the cyclic prefixat the beginning of the symbol), intersymbol interference is decreased.

A cyclic prefix may be generally described as one of a normal cyclicprefix with 6 OFDM symbols and a length of 4.7 μs or an extended cyclicprefix with 7 OFDM symbols and a length of 16.6 μs. Generally, a longercyclic prefix (i.e., the extended cyclic prefix) is implemented incircumstances when multipath propagation is abundant. While normalcyclic prefix, and to a greater extent, extended cyclic prefix, protectagainst ISI, enablement of either type of cyclic prefix decreases userthroughputs and comes with a power penalty. For example, when normalcyclic prefix is enabled, data rate transfer may be 8 Megabits/second,whereas when normal cyclic prefix is turned off, data rate transfer maybe 9 or 10 Megabits/second.

Traditional solutions to reducing ISI within a channel include staticenablement of cyclic prefix (i.e., cyclic prefix remains turned on untilmanually turned off by an operator). Static implementation of cyclicprefix is neither convenient nor efficient and is not easily adaptableto changing circumstances within wireless channels. Thus, improvementsare still needed.

Turning now to FIG. 1, a block diagram of an illustrative mobile deviceis provided and referenced generally by the numeral 100. Although somecomponents are shown in the singular, they may be plural. For example,mobile device 100 might include multiple processors or multiple radios,etc. As illustratively shown, mobile device 100 includes a bus 110 thatdirectly or indirectly couples various components together includingmemory 112, a processor 114, a presentation component 116, a radio 117,input/output ports 118, input/output components 120, and a power supply122.

Memory 112 might take the form of one or more of the aforementionedmedia. Thus, we will not elaborate more here, only to say that memorycomponent 112 can include any type of medium that is capable of storinginformation in a manner readable by a computing device. Processor 114might actually be multiple processors that receive instructions andprocess them accordingly. Presentation component 116 includes the likesof a display and a speaker, as well as other components that can presentinformation (such as a lamp (LED), or even lighted keyboards).

Radio 117 represents a radio that facilitates communication with awireless telecommunications network. Illustrative wirelesstelecommunications technologies include CDMA, 1XA, GPRS, TDMA, GSM,WiMax technology, LTE, LTE Advanced and the like. In some embodiments,radio 117 might also facilitate other types of wireless communicationsincluding Wi-Fi communications and GIS communications, and othernear-field communications.

Input/output port 118 might take on a variety of forms. Illustrativeinput/output ports include a USB jack, stereo jack, infrared port,proprietary communications ports, and the like. Input/output components120 include items such as keyboards, microphones, touchscreens, and anyother item usable to directly or indirectly input data into mobiledevice 100. Power supply 122 includes items such as batteries, fuelcells, or any other component that can act as a power source to powermobile device 100.

FIG. 2 provides an exemplary network environment suitable for use inimplementing embodiments of the present invention and is referencedgenerally by the numeral 200. The network 200 includes a mobile device202, a base station 210, and a core network 204. The network 200 is butone example of a suitable network environment and is not intended tosuggest any limitation as to the scope of use or functionality of theinvention. Neither should the network environment be interpreted ashaving any dependency or requirement relating to any one or combinationof components illustrated.

Mobile device 202, in one embodiment, is the type of device describedherein in connection with FIG. 1. The mobile device 202 may supportmultiple technologies such as CDMA 1XA, GPRS, EvDO, TDMA, GSM, WiMaxtechnology, LTE, LTE Advanced, and the like. Alternatively, the mobiledevice 202 may support one type of technology, such as LTE (LTE and/orLTE Advanced). Any and all such aspects, and any combination thereof,are contemplated as being within the scope of the invention. The mobiledevice 202 may subscribe to services offered by the core network 204. Assuch, the mobile device 202 may be in communication with the basestation 210 via wireless-telecommunications links such as, for example,wireless-telecommunications link 226. The mobile device 202 maycommunicate with the base station 210 via thewireless-telecommunications link 226 to facilitate attachment of themobile device 202 to the base station 210. Once attached, the mobiledevice 202 may also use the wireless-telecommunications link 226 to sendand/or receive voice call information and/or data information as well asinformation concerning device capabilities. In one aspect, the mobiledevice 202 may utilize the wireless-telecommunications link 226 to sendCQI reports that indicate a level of ISI within the network to the basestation 210.

The base station 210 includes hardware and bandwidth(s) of a specifiedfrequency. Although the term “base station” is used throughout thisapplication, equivalent terms may include radio access node, eNodeB, andNode B. For example, if the wireless communications system utilizes LTE,the base station 210 would be termed eNodeB. The hardware includes, forexample, the actual radio mast or tower, as well as antennas,transceivers, GPS receivers, electrical power sources, digital signalprocessors, control electronics, and the like that are associated withthe radio tower. The RF spectrum bandwidth may comprise one or morechannels. With respect to the disclosure provided herein, the term“channel” refers to a signal transmission medium that may include anupload spectrum and a download spectrum.

Besides being in communication with the mobile device 202 via thewireless-telecommunications link 226, the base station 210 may be incommunication with other base stations (not shown) in the network viaadditional telecommunications links (not shown), which may be wired orwireless to facilitate handoffs or handovers between the different basestations when the mobile station 202 moves from one base station to thenext. The base station 210 may also communicate with the core network214 via wired and/or wireless telecommunications links such as, forexample, telecommunications link 228.

The mobile device 202 can utilize network 204 to communicate with othercomputing devices (e.g., a mobile device(s), a server(s), a personalcomputer(s), etc.). In embodiments, the network 204 is atelecommunications network(s), or a portion thereof. Atelecommunications network might include an array of devices orcomponents, some of which are not shown so as to not obscure morerelevant aspects of the invention. Components such as terminals, links,and nodes (as well as other components) can provide connectivity in someembodiments. Network 204 can include multiple networks, as well as beinga network of networks, but is shown in more simple form so as to notobscure other aspects of the present invention. The network 204 can bepart of a telecommunication network that connects subscribers to theirimmediate service provider. In embodiments, the network 204 can beassociated with a telecommunications provider that provides services touser devices, such as mobile device 202. For example, the network 204may provide voice services to user devices or corresponding users thatare registered or subscribed to utilize the services (e.g., the network204) provided by a telecommunications provider. The network 204 can beany communication network providing voice and/or data service(s), suchas, for example, a 1× circuit voice, a 3G network (e.g., CDMA, CDMA8,WCDMA, GSM, UMTS), or a 4G network (WiMAX, LTE, HSDPA).

As shown in FIG. 2, the base station 210 also includes illustrativecomponents for carrying out embodiments of the present invention. Thebase station 210 comprises a receiving component 212, a determiningcomponent 214, and an adaptive convolution component 216. Whileparticular components may be used, embodiments of the present inventionare not limited to such components, and such components are shown forexemplary purposes only.

The receiving component 212 is configured to receive information aboutlevels of ISI within a channel. In one embodiment, informationassociated with levels of ISI is received from CQI reports or othersignal quality measurement reports. CQI reports are generated byindividual mobile communication devices. CQIs may indicate the number ofusers operating within a cell or network, the location of the users, thenumber and identity of users at the cell edge and/or the number andidentity of roaming users operating within a cell, and the like.Information contained within CQI reports may be dynamically (i.e.,automatically and in real-time) updated. The receiving component 212 isalso configured to receive information indicating a number of cell edgeusers or roaming users communicating with a base station via a wirelesschannel. Such information may also be distilled from signal qualitymeasurement reports (e.g., CQI reports).

The receiving component 212 is configured to receive a predeterminedthreshold level of ISI for a channel from, for example, the network 204.The predetermined threshold level of ISI may generally be defined as thelevel at or above which cyclic prefix should be enabled and the levelbelow which cyclic prefix should be disabled within a channel. Thereceiving component 212 is also configured to receive an indication of athreshold number of cell edge users and/or roaming users that maycommunicate via the wireless channel before cyclic prefix is disabledwithin the channel. The predetermined number of cell edge users and/orroaming users may also be received from the network 204. Thepredetermined threshold number of cell edge and/or roaming users maygenerally be defined as a number of cell edge and/or roaming users at orabove which user throughputs decrease to below minimally-acceptablestandards.

The predetermined threshold level of ISI and the predetermined thresholdnumbers of cell edge and/or roaming users are configurable by thenetwork 204. The predetermined threshold level of ISI is based uponlevels of distortion within a channel and/or signal quality associatedwith the channel. The predetermined threshold numbers of cell edge usersand/or roaming users may be based upon a ratio of cell edge users tonon-cell edge users and/or roaming users to non-roaming users. Forexample, the predetermined threshold number of cell-edge users may be anumber at which cell edge users outnumber non-cell edge userscommunicating via a given channel. As well, the predetermined thresholdnumber may take into account combined numbers of cell edge users androaming users communicating via a given LTE channel. The predeterminedthreshold numbers may also be based on characteristics of the basestation 210. For example, the processing load of the base station 210 orthe number of LTE channels carried by the base station 210 may affectthe predetermined threshold numbers. As well, predetermined thresholdnumbers of cell edge users or roaming users may be the same or differentfor each downlink LTE channel carried by the base station 210. Whiledescribed herein as a single levels and single numbers, it will beunderstood that the threshold levels and numbers may include a range oflevels or numbers. Many additional factors may contribute to adetermination of a threshold level of ISI or threshold numbers of celledge or roaming users, and the examples provided herein are not meant tobe limiting.

The determining component 214 is configured to determine that the levelsof ISI within the channel are above, the same as, or below thepredetermined threshold level of ISI. When the levels of ISI within thechannel are at or above the threshold level of ISI, the determiningcomponent 214 determines that cyclic prefix should be enabled (i.e.,turned on), and the adaptive convolution component 216 dynamically turnscyclic prefix on. When the levels of ISI within the channel are belowthe threshold level of ISI, the determining component 214 determinesthat cyclic prefix should be disabled (i.e., turned off), and theadaptive convolution component 216 automatically turns cyclic off. Inthis way, the dynamic turning on and off of cyclic prefix mitigatespower penalties associated with static enablement of cyclic prefix.

The determining component 214 is also configured to determine that, whenthe number of cell edge users or roaming users communicating via awireless channel exceeds the predetermined threshold number of cell edgeusers and/or roaming users for the channel, cyclic prefix should bedisabled. Upon making such a determination, the adaptive convolutioncomponent 216 dynamically disables cyclic prefix within the channel. Insome embodiments, when the number of cell edge users or roaming usersexceeds the predetermined threshold numbers of cell edge users and/orroaming users, cyclic prefix is disabled only if ISI within the channelalso does not exceed the predetermined threshold level of ISI for thechannel. In such embodiments, if ISI does exceed the predeterminedthreshold level of ISI, cyclic prefix will remain enabled, even thoughthe number of cell edge or roaming users utilizing the channel exceedsthe predetermined number of cell edge or roaming users for the channel.

The determining component 214 is also configured to determine signalquality and distortion levels associated with different LTE channels, aswell as identities of users communicating via different LTE channels.Such information may be gleaned from one or more signal qualitymeasurement reports, for example. In this way, the determining component214 may determine that some LTE channels are experiencing higher ISIlevels (i.e., distortion levels) than other LTE channels. Thedetermining component 214 may also determine that some LTE channels aretransmitting signals to higher numbers of cell edge users than other LTEchannels carried by a same base station 210. In this same vein, thedetermining component 214 may determine that a first set of users areexperiencing decreased user throughputs (i.e., data and/or voicetransmission speed rates) than a second set of users, and that the firstset of users are communicating via a different wireless channel than thesecond set of users. Additionally, the determining component 214 isconfigured to determine that the first set of users are in a differentgeographic location than the second set of users based on informationcontained within the signal quality measurement reports.

As an example used for illustrative purposes only, the determiningcomponent 214 is configured to determine that a first channel isexperiencing levels of ISI that are higher than the predeterminedthreshold level of ISI. The determining component 214 is also configuredto determine that at least a second channel is experiencing levels ofISI that are below the predetermined threshold level of ISI. Based onsuch determinations, the determining component 214 is configured todetermine that cyclic prefix should be enabled within the first channeland disabled within at least the second channel. The adaptiveconvolution component 216 would then, in real-time, enable cyclic prefixin the first channel and disable cyclic prefix within at least thesecond channel. Similarly, the determining component 214 is configuredto determine that at least a first channel is experiencing levels of ISIabove the predetermined threshold level, while at least a second channelis carrying above the predetermined threshold number of cell edge users.The determining component 214 may determine, therefore, that cyclicprefix should be enabled within the first channel and disabled within atleast the second channel. As with the first example, the adaptiveconvolution component 216 would then, in real-time, enable cyclic prefixin at least the first channel and disable cyclic prefix within at leastthe second channel.

Turning now to FIG. 4, FIG. 4 depicts a flow diagram illustrating amethod for dynamically enabling cyclic prefix based on distortion levelswithin a network. At a step 410, one or more inputs indicating a levelof ISI within a channel are received at a base station, such as the basestation 210 of FIG. 2. These inputs may be received from a CQI reportgenerated by each mobile communication device communicating via thechannel. At a step 420, an indication of a predetermined threshold levelof ISI for the channel is also received. The threshold level may bepredetermined by a service provider, as described above.

At a step 430, it is determined that ISI within the channel is at alevel greater than or equal to the threshold level of ISI. At a step440, upon determining that ISI within the channel is greater than orequal to the threshold level of ISI, cyclic prefix is dynamicallyenabled (i.e., turned on). Although not shown, additional inputs may bereceived. For example, after enabling cyclic prefix, another indicationof the level of ISI within the channel may be received. Subsequently, adetermination may be made that the level of ISI within the channel isbelow the predetermined threshold level of ISI. Upon determining thatISI within the channel is below the predetermined threshold level,cyclic prefix may be disabled. In this way, cyclic prefix may be enabledand/or disabled for all channels within a cell, for channels leading toparticular geographic locations, or for fewer than all channels within acell and/or carried by a particular base station.

Turning now to FIG. 5, FIG. 5 depicts a flow diagram illustrating amethod for disabling cyclic prefix (i.e., introducing linear convolutionwithin a channel) when a number of cell edge users communicating via achannel exceeds a predetermined threshold number of cell edge users forthe channel. The predetermined threshold number is a number at or abovewhich user throughputs for a given user (e.g., cell edge users) decreaseto below minimally-acceptable standards. The predetermined thresholdnumber may be determined by a service provider or a network, such asnetwork 204 of FIG. 2.

Initially, at a step 510, one or more inputs indicating a number of celledge users communicating via the channel is received. The inputs may begleaned from CQI reports generated by and communicated from mobilecommunication devices associated with each of the cell edge users. At astep 520, one or more inputs indicating a predetermined threshold numberof cell edge users that may utilize the channel is received.

At a step 530, it is determined that the number of cell edge usersutilizing the channel is at or above the threshold number of cell edgeusers that may utilize the channel before the cell edge users experienceless than minimally-acceptable user throughputs. Upon making such adetermination, at a step 540, cyclic prefix is disabled to provideadditional bandwidth and power to the cell edge users. In someembodiments, cyclic prefix is only disabled when ISI within the channelis below a predetermined threshold level of ISI for the channel, asdescribed above. Although not shown, the method depicted in FIG. 5applies equally for roaming users as it does for cell edge users.

Many different arrangements of the various components depicted, as wellas components not shown, are possible without departing from the scopeof the claims below. Embodiments of our technology have been describedwith the intent to be illustrative rather than restrictive. Alternativeembodiments will become apparent to readers of this disclosure after andbecause of reading it. Alternative means of implementing theaforementioned can be completed without departing from the scope of theclaims below. Certain features and sub-combinations are of utility andmay be employed without reference to other features and sub-combinationsand are contemplated within the scope of the claims.

The invention claimed is:
 1. A system for dynamically disabling orenabling a cyclic prefix based on signal quality within one or morechannels, the system comprising: a base station having one or morehardware devices including one or more processors; and one or morecomputer storage media storing computer-useable instructions that, whenexecuted by the one or more processors, implement a method comprising:receiving signal quality measurements for a channel carried by the basestation from one or more user devices utilizing the channel; determininga signal quality level for the channel based on the received signalquality measurements; receiving an indication of a predeterminedthreshold level of a signal quality for the channel; determining thatthe signal quality level for the channel is at one of a level below or alevel above the predetermined threshold level; enabling the cyclicprefix when the signal quality level for the channel is at one of eitherthe same level or the level above the predetermined threshold level; anddisabling the cyclic prefix when the signal quality level for thechannel is at the level below the predetermined threshold level, whereindisabling the cyclic prefix removes all cyclic prefixes within thechannel.
 2. The system of claim 1, wherein disabling the cyclic prefixincreases an available bandwidth for the channel.
 3. The system of claim1, wherein disabling the cyclic prefix increases a data transfer ratewithin the channel.
 4. The system of claim 1, wherein enabling thecyclic prefix decreases user throughputs, and wherein disabling thecyclic prefix increases user throughputs.
 5. The system of claim 1,wherein the signal quality measurements indicate a level of intersymbolinterference (ISI).
 6. The system of claim 1, wherein the cyclic prefixis a download cyclic prefix for a download spectrum for the channel. 7.A method for dynamically disabling or enabling a cyclic prefix at a basestation in a wireless network, the method comprising: receiving signalquality measurements from one or more mobile devices in communicationwith the base station; determining a signal quality level based on thereceived signal quality measurements; receiving an indication of anumber of non-roaming users and a number of roaming users incommunication with the base station; determining a processing load ofthe base station and a number of channels carried by the base station;determining a signal quality threshold level for the cyclic prefix basedon one or more of the processing load and the number of channels carriedby the base station; determining a non-roaming and roaming thresholdnumber for the cyclic prefix based on one or more of the processing loadand the number of channels carried by the base station; enabling thecyclic prefix when at least one of: the signal quality level is at alevel above the signal quality threshold level; the number ofnon-roaming users is at a level above the non-roaming and roamingthreshold number; and the number of roaming users is at the level abovethe non-roaming and roaming threshold number; and disabling the cyclicprefix such that all cyclic prefixes within a channel carried by thebase station are removed when at least one of: the signal quality levelis a level below the signal quality threshold level; the number ofnon-roaming users is at a level below the non-roaming and roamingthreshold number; and the number of roaming users is at the level belowthe non-roaming and roaming threshold number.
 8. The method of claim 7,wherein the signal quality level, the number of non-roaming users, andthe number of roaming users are dynamically and automatically updated.9. The method of claim 7, wherein disabling the cyclic prefix increasesan available bandwidth for the channel.
 10. The method of claim 7,wherein disabling the cyclic prefix increases a data transfer ratewithin a channel carried by the base station.
 11. The method of claim 7,wherein enabling the cyclic prefix decreases user throughputs for achannel carried by the base station, and wherein disabling the cyclicprefix increases user throughputs the channel carried by the basestation.
 12. The method of claim 7, wherein the cyclic prefix is adownload cyclic prefix for a download spectrum for a channel carried bythe base station.
 13. A method for dynamically disabling or enabling acyclic prefix in one or more channels carried by a base station in awireless network, the method comprising: receiving signal qualitymeasurements from one or more mobile devices in each of a first channeland a second channel carried by the base station; determining a signalquality level for the first channel and a signal quality level for thesecond channel based on the received signal quality measurements;receiving an indication of a first signal quality threshold level forthe first channel and a second signal quality threshold level for thesecond channel; enabling the cyclic prefix when at least one of: thesignal quality level for the first channel is at a level above the firstsignal quality threshold level; or the signal quality level for thesecond channel is at a level above the second signal quality thresholdlevel; and disabling the cyclic prefix such that all cyclic prefixes areremoved when at least one of: the signal quality level for the firstchannel is at a level below the first signal quality threshold level; orthe signal quality level for the second channel is at a level below thesecond signal quality threshold level.
 14. The method of claim 13,wherein disabling the cyclic prefix increases an available bandwidth.15. The method of claim 13, wherein disabling the cyclic prefixincreases a data transfer rate.
 16. The method of claim 13, whereinenabling the cyclic prefix decreases user throughputs, and whereindisabling the cyclic prefix increases user throughputs.
 17. The methodof claim 13, wherein the cyclic prefix is a download cyclic prefix for adownload spectrum.